Closed-system single-acting fluidoperated pump



May 10, 1960 c. J. COBERLY CLOSED-SYSTEM SINGLE-ACTING FLUID-OPERATED PUMP Filed Dec. 2 1955 8 Sheets-Sheet 1 aA/QE/VCE CI Q3524 By ///s flr'r'oe/vsyst Al ae/5; Mean, i asme 6 12212915:

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CLOSED-SYSTEM SINGLE-ACTING FLUID-OPERATED PUMP Filed Dec. 2, 1955 8 Sheets-Sheet 3 12. a 11:6. fire: 10.

1 J34- 174 i I L/I2ENCE COBEQLM, IA/rEA/rae.

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May 10, 1960 c. J. COBERLY CLOSED-SYSTEM SINGLE-ACTING FLUID-OPERATED PUMP Filed Dec. 2, 1955 8 Sheets-Sheet 4 5y f/ls-flrraeusys.

I HE/eels, 16/56, 0515? 33295 y 10, 1950 c. J. COBERLY 2,935,953

CLOSED-SYSTEM SINGLE-ACTING FLUID-OPERATED PUMP May 10, 1960 c. .1. COBERLY 2,935,953

CLOSED-SYSTEM SINGLE-ACTING FLUID-OPERATED PUMP Filed Dec. 2, 1955 v 8 Sheets-Sheet 6 g/W/M/ CZAQEA/z-E cl. E0552; y,

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May 10, 1960 c. J. COBERLY CLOSED-SYSTEM SINGLE-ACTING FLUID-OPERATED PUMP Filed Dec. 2, 1955 8 Sheets-Sheet 7 m f s 62 4EEA/CE cl @EEQL United States Patent() "ice CLOSED-SYSTEM SINGLE-ACTING FLUID- OPERATED PUNIP Clarence J. Coberly, San Marin'o, Califl, assignor to Kobe,

Inc., Huntington Park, Calitl, a corporation of California Application December 2, 1955, Serial No. 550,538 I 18 Claims. (Cl. 103-46) The present invention relates in general to fluidoperated bottom hole pumps for oil wells and, for con venience, will be considered herein as embodied in a single-acting free pump for use in a closed system with the understanding that various features thereof maybe embodied in pumps of other types and for other purposes.

As general background, it will be understood that a fluid-operated oil well pump includes hydraulically recip rocable engine and pump piston means, the piston means being displaced, at least in one direction, by an operating fluid, such as clean crude oil, under high pressure delivered to the pump through a supply or power oil tubing set in the well. The piston means operates to draw production fluid from the well into the pump and to discharge it therefrom at a pressure equal to the static head of the fluid in the production tubing plus the friction losses. The spent operating fluid is also discharged from the pump at a pressure equal to the static head of the fluid in the power oil return tubing plus friction losses, the spent operating fluid and the production fluid discharged by the pump being conveyed to the surface separately through return and production tubings, respectively, in a closed system. It should be pointed out that the static head of the fluid in the power oil supply tubing is the same as that of the power oil return tubing, but the actual pressure is greater in the supply tubing by the amount required to operate the bottom hole pump. It is this difference in pressure applied to the engine piston means that actuatesthe unit. In a single-acting pump, the piston means discharges production fluid during movement thereof in one direction only, i.e., during the working stroke of the pump,no production fluid being discharged during movement of the piston means in the opposite direction, i.e., during the return stroke of the pump. To round out the introductory statement'in the preceding paragraph, a free-pump system is one in which the pump is movable between the surface and its operating position in the well through one of the supply, return and production tubings mentioned, the pump preferably being moved between the surface and its operating.

position hydraulically.

A general object of the present invention is to provide a pump and pump system of the nature outlined in the preceding paragraph. i

As more specific background, the return stroke of a single-acting pump has been effected heretofore either by gravity, or by the application of operating-fluid pressure from the supply tubing to the piston means of the pump. Return by gravity is possible only if the return stroke is the down stroke and if the pump is oriented substantially vertically. Even under such conditions, however, return by gravity is not reliable and may be time consuming,

particularly where the production fluid is a heavy, viscous oil. Efi'ecting the return stroke by applying the operating-fluid pressure from the supply column'to the piston means of the pump overcomes the disadvantages of tion of the return stroke, but has other disadvantages.

Perhaps the most serious disadvantage is that utilizing the sure applied on the return stroke yet as much as 20% of' the operating fluid supplied to the system by the pumping equipment at the surface may be used up in effecting the gravity return and is effective irrespective of the direcstructural problems engendered by such use.

cylinder, particularly with viscous oils. vention makes it possible to have the speed of the return return stroke of the piston means, thereby making utiliza-l tion of the operating fluid supplied by such pumping equipment only about eflective, which represents a considerable waste of power. Another disadvantage of the prior art is that, since the operating-fluid pressure is quite high, the structure of the piston means must be designed to withstand the forces developed during the re turn stroke when the operating fluid pressure is utilized to effect such stroke. In single-acting pumps wherein the returnstroke is produced by applying the operating-fluid pressure to the area of a tube or rod, such as a rod interconnecting engine and pump plungers of the piston means, such tubes or rods must be sufliciently large to withstand the loads on the working stroke, and with operating pres sure applied to the areas of such tubes or rods the force is greater than that required to eflect the return stroke and hence the return speed is excessive, as is the power wasted, all of which is undesirable. "If the area of a valve rod is used as in my Patent 2,291,880, the column strength of this rod must be suflicient to apply the force required for the return stroke. If the slenderness ratio of this column and the stroke length of the pump are both kept within practical limits, the rod area will still be excessive for the work to be done, although it may be substantially less than in the above case. Another disadvantage of the prior art is that, when the operating fluid from the supply tubing is utilized to produce the return stroke, no control of the speed of the piston means during the return stroke independent of the control of the speed thereof during the working stroke exists, which is also undesirable.

In the light of the foregoing, primary objects of the present inventionare to provide a single-acting fluidoperated pump in which the return stroke is efiected in a positive manner without the use of operatingfluid from the supply tubing, and in which the speedof the return stroke is controllable, preferably from the surface, independently of the speed of the working stroke. I

Thus, the present invention, by avoiding the use o operating fluid from-the supply column to produce the return stroke, eliminates the operating-fluid loss and Also, by providing an independent control for the speed of the piston means during the return stroke, the speed of the piston means during such stroke may be any appropriate value and is not dependent on such factors as the speed during the working stroke, variations in the operatingfluid pressure (such as those due to variations inwell depth), the various areas of the piston means, and the like. With the present invention, the speed of the return stroke is controlled solely by the operator of the pumping system, and may be as high or as low as desired for varying pumping conditions. In general, a high-speed return stroke is desired so that the working stroke may take place at a low speed Without increasing the total time consumed by the two strokes, a low speed during. the working stroke resulting inbetter filling of the pump The present instroke as high as safety considerations permit, Without Patented May 10, 1960 3 regard to any other considerations. Alternatively, the speed of the return stroke may be as low as desired.

The foregoing primary objects of the present invention are; attained by utilizing the pressures in the return and production columns to apply to the piston means the pressure force differential necessary to return the piston means, which is a basic object of the invention.

More particularly, an important object of the invention is to apply the pressures in the return and production columns to equal and opposite areas of the piston means and tomaintain a pressure differential between the return and production columns to produce the pressure force differential necessary to effect the return stroke.

. Another important object is to provide control means at the surface for controlling the pressure differential between the production and return columns, thereby controlling the pressure force differential applied to the piston means during the return stroke and thus controlling the speed of the return stroke.

Another object is to effect the return stroke in the foregoing manner by maintaining the pressure in the return column higher than that in the production column by maintaining a back pressure on the return column.

Another object is to provide a single-acting pump of the foregoing nature wherein the piston means includes engine and pump plungers respectively reciprocable in engine and pump cylinders and interconnected by a rod which, in effect, provides the equal and opposite areas mentioned above.

Another object of the invention is to provide a singleacting pump in which the upper end of the piston means, i.e., the upper end of the engine plunger, is in constant communication with the return tubing, and wherein the lower end of the piston means, i.e., the lower end of the pump plunger, is alternately exposed to the pressure in the well and the pressure in the production column.

Another object is to provide a single-acting pump in which a downwardly-facing area of the piston means intermediate the upper and lower ends thereof, i.e., the annular area of the lower end of the engine plunger produced by the connecting rod, is alternately exposed to the pressure in the supply column and the pressure in the return column, and in which an upwardly-facing area intermediate the upper and lower ends of the piston means, i.e., an annular area of the upper end of the pump plunger produced by the connecting rod, is in constant communication with the production tubing.

With the foregoing construction, when the annular area .at the lower end of the engine or motor plunger is exposed to the operating-fluid pressure in the supply tubing, the piston means moves upwardly to accomplish its working stroke. However, when the annular area at the lower end of the engine plunger is connected to the return tubing, the piston means is moved downwardly to accomplish its return stroke. This is due to the fact that the higher, return pressure at the upper end of the piston means acts downwardly on the area of the connecting rod in opposition to the upward action, on the area of the connecting rod, of the lower, production pressure at the lower end of the piston means. Thus, the return stroke of the piston means is produced with only the return-column and the production-column pressures applied to the piston means, which is an important feature.

Turning now to a different phase of the present invention, an important object thereof is to provide a fluidoperated pump which includes a fluid-operated engine fluid-operated pump of the immediately-preceding nature 4 which is a single-acting pump embodying the features set forth in preceding paragraphs.

An important object is to provide a fluid-operated pump having its engine valve intermediate its engine and pump sections and having an engine valve which includes a valve member encircling and controlled by a rod connecting the engine and pump plungers. A related object is to provide a valve member which is hydraulically movable between its operating positions to effect the two strokes of the engine plunger, and to provide a connecting rod between the engine and pump plungers which acts as a pilot valve for controlling the application of fluid pressure to the valve member to move it between its operating positions.

Another object is to provide a fluid-operated pump in which a rod interconnecting engine and pump plungers is slidable in a tubular valve member of the engine valve, and wherein the valve member is slidable on the rod in one direction to produce movement of the engine and pump plungers in such direction and is slidable on the rod in the opposite direction to produce movement of the engine and pump plungers in the opposite direction. With this construction, the valve member always moves in the same direction as the rod, except at the ends of the working and return strokes, so that friction between the rod and the valve member constantly biases the valve member toward its proper operating position, which is an important feature.

Another object is to provide a single-acting pump having an engine valve which is located intermediate engine and pump sections of the pump, and which has a three speed governing action during the working stroke of the pump and a single-speed action during the return stroke thereof.

Another object of the invention is to provide a fluidoperated pump having a differential-area engine valve intermediate engine and pump sections of the pump.

Another object of importance is to provide a differential-area engine valve including a tubular valve member having a uniform external diameter and a variable internal diameter to provide a plurality of pressure areas.

More particularly, an object is to provide a valve member of the foregoing nature having a uniform outside diameter and having two different diameters adjacent the respective ends thereof, whereby to provide the valve member with a large annular area at one end thereof, a small, outer annular area at the other end thereof, and a small, inner annular area facing in the same direction as the outer annular area.

Another object of the invention is to provide a differential-area engine valve of the foregoing nature in which a valve rod extends through the valve member and has a diameter substantially equal to the smaller of the inside diameters of the valve members.

Another object is to provide a differential-area engine valve of the nature outlined in the preceding paragraph including a floating, tubular cylindrical member making a sliding fit with the valve rod and making a sliding fit with the larger of the inside diameters of the valve member, this floating member serving to separate the inner and outer annular areas of the valve member.

Another object is to provide a differential-area engine valve including a tubular valve member having a large annular area facing in one direction and smaller, inner and outer annular areas facing in the opposite direction and respectively exposed to different pressures, the inner and outer annular areas mentioned being provided by forming the valve member with different inside diameters and a substantially uniform outside diameter. A related object is to provide a differential-area engine valve where in the large annular area is alternately exposed to the different pressures mentioned, whereby to produce reciprocatory movement of the valve member.

Another object is to provide a fluid-operated pump having a differential-area engine valve of the foregoing nature and having the other features hereinbefore discussed.

Another object isto provide a'fluid-operated pump having an engine valve intermediate motor and pump sections of the pump, the motor and pump sections in cluding motor and pump plungers connected by a rod which is sealed by floating bushings encircling the rod between the engine valve and the engine and pump plungers.

Another important object of the present invention is to provide an engine valve having a component which includes inner and outer sleeves secured together with a fluid-tight fit therebetween, there being fluid passages in one of the sleeves at the interface between the sleeves, preferably formed by providing the inner sleeve with grooves in its exterior surface which are closed by the outer sleeve. The two sleeves may be'secured together in a fluid-tight manner by pressing the inner sleeve into the outer, by shrinking the outer sleeve onto the inner, or the like. 1

Another object is to provide an engine valve having :a two-sleeve component of the foregoing nature which constitutes a valve body for the tubular valve member lhereinbefore discussed.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which Will be evident to those skilled in the art in the light of this :specification, may be attained with the exemplary embodiment of the invention which is illustrated in the accompanying drawings and which is described in detail hereinafter. Referring to the drawings:

Fig. l is a vertical sectional view, on a reduced scale, "illustrating the present invention as installed in a'well;-

Figs. 2, 3 and 4 are enlarged, horizontal sectional views :respectively taken along the arrowed lines 22, 33 :and 44 of Fig. 1;

Figs. 5 and 6 are vertical sectional views respectively taken along the irregular arrowed lines 5-5 and 6'--6 of .Fig. 2, and taken at the same level;

Fig. 7 is a downward continuation of Fig. 5;

Figs. 8, 9 and are vertical sectional views respectively taken along the irregular arrowed lines 8-8, 99 :and 101li of Fig. 3 and taken at the same level, Fig. 8 being a downward continuation of Fig. 7;

Fig. 11 is a vertical sectional view taken along the irregular arrowed line 11-11 of Fig. 4, and is a downward continuation of Fig. 8;

Figs. 12 and 13 are enlarged, fragmentary vertical :sectional views respectively taken along the arrowed lines '12-12 and 1313 of Fig. 8, Fig. 12 illustrating a pump piston means of the invention and Fig. 13 illustrating an engine valve thereof;

Fig. 14 is similar to Fig. 13, but illustrates various components of the engine valve in other operating positions;

Figs. 15 and 16 are fragmentary, enlarged, vertical sectional views respectively duplicating the upper and lower halves of Fig. 13;

Figs. 17, 18, 19 and are transverse sectional views respectively taken along the arrowed lines 17--17, 18-48, 1919 and 2-0-20 of Fig. 15;

Figs. 21 and 22 are horizontal sectional views respectively taken along the arrowed lines 2121 and 2222 of Fig. 16; and

Figs. 23 and 24 are simplified, diagrammatic views illustrating the operation of the fluid-operated pump of the invention and showing various components thereof in different operating positions.

General description Referring first to Fig. 1 of the drawings, the numeral 30 designates a casing set in a well bore 32, the lower end of the casing being shown perforated to admit production fluid from a productive formation 34. The casing 30 terminates at its upper end in a casing head'36from which a tubing system 38 is suspended in the casing. The tubing system 38 supports a bottom-hole assembly 401with- Zin the lower end of the casing 30, the bottom-hole assembly housing a fluid-operated single-acting free pump 42, Fig. 2 et seq., when this pump is in its operating position in the well. The pump 42 is supplied with operating hid under high pressure through a supply or power oil tubing 44 which forms part of the tubing system 38, this tubing system also including a power oil return tubing 46 through which spent operating fluid discharged by the pump 42 is returned to the surface. A production tubing 48 completes the tubing system 38, the production tubing performing the function of conveying the production fluid discharged by the pump 42 upwardly to the surface, and also performing the function of conveying the pump 42 between the surface and its operating position in the well. Since the tubing 48 is utilized to convey the pump 42 between its operating position and the surface, this tubing is the largest of the three tubings 4,4, 46 and 48, so

that utilizing it as the production tubing as well minimizes production-fluid friction, which is a feature of the invention.

The tubing system 38 terminates at its upper end in a control device 50 havingvalve means, not specifically shown, for connecting the supply, return and production tubings 44, 46 and 48 to supply, return and production pipes 52, 54, and 56, respectively, during operation of the pump 42, the supply pipe leading to a suitable source, not shown, of operating fluid underhigh pressure, and the return and production pipes leadingto suitable points of disposal for the spent operating fluid and the production fluid. As will be discussed hereinafter in more detail, the aforementioned valve means of the control device 50 may be operated to reverse the flow through the return pipe 54 and the return tubing 46 to displace the pump 42 upwardly through the production tubing 48 to the surface when it is desired to remove the pump from the well. The control device 50 also provides means, such as valve means, not shown, for maintaining a fluid pressure diiferential between the fluid columns in the return and production tubings 46 and 48 to effect the return stroke of an engine and pump piston means 58 in the pump 42, the working stroke of the piston means being effected by operating fluid under pressure from the supply tubing, as will be discussed hereinafter. Preferably, the return stroke of the piston means 58 is produced by maintaining the pressurein the fluid column in the return tubing 46 higher than the pressure of the fluid column in the production tubing 48, as by applying a back pressure to the return tubing 46 by means of the control device.

Considering the pump 42 and the bottom hole assembly 40, generally, the pump includes an upper, engine or motor section 60, Fig. 5, an intermediate engine valve 62, Fig. 8, for alternately applying the fluid pressures in the supply and return tubings 44 and 46 to the piston means 58 to alternately produce the working and return strokes thereof, and a pump section 64, Figs. 8 and v11, for pumping production fluid from the well into the production tubing 48. The bottom-hole assembly 40 includes, generally, an upper sealing collar 66, Fig. 5, which receives the upper end of the engine section 60 of the pump 42, an intermediate sealing collar 68, Fig. 8, which receives the engine valve 62 located intermediate the engine and pump sections 60 and 64, and a lower sealing collar, or bottom shoe 70, Fig. 11, which receives the lower end of the pump section 64 of the pump.

The bott m-hole assembly 40 Considering the bottom-hole assembly 40 in more detail, and taking up the path followed by the operating 7 end of the intermediate sealing collar 68, and which is sealed relative to this sealing collar by an O-ring 76. Thus, operating fluid under pressure from the supply tubing 44 flows through the upper scaling collar 66 and the pipe 72 into the bore 74, and, from this bore, it flows through a passage 78 into a main bore 80 through the intermediate sealing collar 68. The engine valve 62 of the pump 42 is disposed in the main bore 80 and provides an operating fluid intake 82 of the pump 42. At the ends of the main bore 80 through the intermediate sealing collar 68 are counterbores 84 and 86 into which are pressed sleeves 88 and 90, the pump 42 carrying O-rings 92 and 94 which engage the sleeves 88 and 90, respectively, when the pump is in its operating position to isolate the operating fluid intake 82 from all but the supply tubing 44.

Tracing the. path of the spent operating fluid through the bottom-hole assembly 40 to the return tubing 46, the return tubing is. threaded at its lower end into a bore 98, Fig. 6, in the upper end of the upper sealing collar 66. This bore communicates through a passage 108 with a longitudinal bore 102 in the upper sealing collar 66. The bore 102 communicates at its lower end with a passa'ge 104 which leads to a bore 106 in the upper sealing collar 66. Pressed into the bore 106 is a sleeve 112 which is engaged by O-rings 114 on the pump 42, the lowermost O-ring 114 isolating the spent operating fluid from other fluids. Extending into the bore 106 in the upper sealing collar 66, and threadedly connected to the upper sealing collar, is a pump housing tube 116, there being an annular space 118 between the engine section 60 of the pump 42 and the pump housing tube 116 which is in constant communication with the return tubing 46 through the bore 106, the passage 104, the bore 102, the passage 100 and the bore 98. The annular space 118 communicates with port means .120 in the pump 42, this port means, as hereinafter described, constantly applying the pressure in the return tubing 46 to the upper end of the piston means 58. i

The annular space 118 betweenthe pump 42 and the pump housing tube 116 extends downwardly into the intermediate sealing collar 68, the lower end of the pump housing'tube 116, as shown in Fig. 8, being threadedly connected to and extending into a counterbore 122 in the upper end of the intermediate sealing collar. The engine valve 62 f the pump 42 is provided with a spent-operating-fluid exhaust 124 which communicates with the counterbore 122, the exhaust 124 thus constantly communicating with-the return tubing 46 through the annular space 118, the bore 106, the passage 104, the bore 102, the passage 100 and the bore 98. The aforementioned O-ring 92 is located between the operating fluid intake 82 and the exhaust 124 for spent operating fluid, thereby separat ing these from each other.

The pressure in the return tubing 46 is also transmitted downwardly into the bottom shoe 70 for the purpose of unseating the pump 42 and moving it upwardly upon reversal of flow through the return tubing, as will be described in more detail hereinafter. For this purpose, the intermediate sealing collar 68 is provided with a passage 126, Fig. 10, which communicates with a longitudinal bore 128 in this sealing collar, the bore 128 communicating at its lower end with a passage 130 which communicates with a bore 132 in the lower end of the intermediate sealing collar. Threaded into the bore 132 is the upper end of a pipe 134 which, as shown in Fig.

11, extends into the upper end of a longitudinal bore 136 in the bottom shoe 70. The lower end of the bore 136 communicates through a passage 138 with a counterbore 140 in the bottom shoe 70. At the upper end of the counterbore 140 is a short bore 142 and above this bore in a counterbore 144 into which is pressed a sleeve 146.

An' O-ring 148 on the pump 42 engages the sleeve 146 to isolate the spent operating fluid in the counterbore 144 from other fluids.

Below the counterbore144 is a counterbore 150 into which is pressed a seat 152 for a standing valve assembly 154 which includes a standing valve 156. The standing valve assembly 154 extends through a short bore 158 in the bottom shoe 70 into an inlet pipe 160 threaded into a counterbore 162 in the lower end of the bottom shoe. The standing valve assembly 154 is similar to that disclosed and claimed in my copending application Serial No. 487,303, filed February 10, 1955, now Patent No. 2,869,470 and, consequently, will be considered only generally herein.

The standing valve assembly 154 provides a tapered seat 164 for the pump 42, or, more specifically, for an inlet plug 166 at the lower end of the pump. As will be discussed in more detail hereinafter, the inlet plug 166 provides an inlet 168 for admitting production fluid from the well into the pump section 64 of the pump 42.

Rounding out the description of the spent operating fluid system, when the flow through the return tubing 46 is reversed, fluid enters the counterbore 140 surrounding the inlet plug 166, and acts upwardly on an annular area of the pump equal to the difierence between the areas indicated by the dimensional arrows 170 and 172, thereby unseating the pump and moving it upwardly. The operation of removing the pump 42 from the well in this manner will be described more completely hereinafter in discussing the operation of the present invention.

Considering the flow of production fluid through the bottom-hole assembly 40, interconnecting the sealing collar 68 and the bottom shoe 70 is a pump housing tube 174, this tube being threadedly connected to the lower end of the sealing collar 68 and being inserted into a counterbore 176 therein below the counterbore 86, as shown in Fig. 8. Referring to Fig. ll, the pump housing tube 174 is threaded at its lower end into the upper end of the bottom shoe 70 and extends into a counterbore 178 therein above the counterbore 144. The pump housing tube 174 provides an annular space 180 around the pump section 64 of the pump, this annular space being sealed at its upper end by the 0-ring 94, Fig. 8, and at its lower end by the O-ring 148, Fig. 11. The annular space 180 communicates with a production fluid outlet 182, Fig. 8, of the pump 42, whereby production fluid discharged by the pump section 64 of the pump enters this annular space. Referring particularly to Fig. 11, the lower end of the annular space 188 communicates, just above the sleeve 146, with a passage 184 in the bottom shoe 70. This passage communicates with a longitudinal bore 186 into which extends the lower end of a pipe 188. Referring to Figs. 3 and 8, the pipe 188 extends upwardly through a bore 189 through the sealing collar 68, and is threaded at its upper end, Fig. 5, into the lower end of the upper sealing collar 66 in communication with a longitudinal bore 190 therein. The upper end of the bore 190 communicates with a radial passage 191 which leads to an external annular groove 192 in the sleeve 112, this groove communicating with radial ports 193 leading to an internal annular groove 194 in the sleeve. Registering with the groove 194 and located between the O-rings 114 is an external annular groove 195 in a fitting 196 which is carried by the pump 42 and which carries the O-rings 114. Radial ports 197 in the fitting 196 connect the groove 195 to an axial bore 198 therein, there being at the upper end of the bore 198 a seat 199 for an upper pump standing valve 200 which functions to prevent backflow of production fluid into the pump 42 when the latter is not completely filled with production fluid. Production fluid flowing upwardly past the standing valve 200 flows through radial ports 201 and 202 into .a counterbore 203 in the sealing collar 66 above the bore flowing upwardly through-the relatively large production tubing with a minimum of frictional resistance.

The" pump 42 Considering the pump 42 now in more detail, it includes at its upper end a packer nose assembly comprising a packer mandrel 204 threaded into the fitting 196 to retain the valve seat 199 in this fitting, the radial ports 201 being formed in the packer mandrel. Mounted on the mandrel 204 is a packer cup 205 of a size to make a fluid tight fit with the inner wall of the production tubing 48 when it is disposed therein, whereby fluid supplied beneath the pump 42 will move the pumpupwardly through the production tubing to the surface. However, when the pump is in its operating position wherein the inlet plug 166 is seated on the seat 164, the packer cup 205 is disposed within the counterbore 203, which is sufliciently large that the production fluid can flow upwardly therepast into the production tubing. The packer mandrel 204 terminates at its upper end in a tapered nose 206 engageable by a pump catcher, not shown, carried by a removable closure 207, Fig. l, mounted on the control device 50.

p The lower end of the fitting 196 is threaded into'and forms a closure for the upper end of an engine cylinder 208, this cylinder having threaded into its lower end a tube 210 which is threaded onto a valve body 212 of the engine valve 62. Reciprocable in the engine cylinder 208 is an engine piston or plunger 214 having end portions 216 and 218 of reduced diameter which enter recesses 220 and 222, respectively, in the fitting 196 and the tube 210 at the ends of the working and return strokes, respectively, of the engine plunger. The end portions 216 and 218 of the engine plunger are only slightly smaller than the recesses 220 and 222 so that, in effect, dashpots are provided for decelerating the engine plunger at the ends of its working and return strokes.

Referring to Fig. 8 in particular, connected to the lower end of the valve body 212 is a tube 224 onto which is threaded a pump cylinder 226 having the production fluid outlet therein adjacent the upper end thereof. The lower end of the pump cylinder 226 has threaded thereinto a fitting 228 which carries the O-ring 148 and into the lower end of which is threaded the inlet plug 166. When the pump 42 is in operation, production fluid from the Well flows through the standing valve assembly 154 and the inlet 168 into the fitting 228. Clarnped between the inlet plug 166 and the fitting 228 is a seat 230 for a lower pump standing valve 232, which is shown as a simple ball valve. Upward movement of the standing valve 232 off its seat is limited by a stop 234 which is pressed into the fitting 228 and which is provided with apertures 236 for production fluid flow therethrough into the pump cylinder 226. The purpose of the standing valve 232 is to prevent backflow out of the pump cylinder 226 without necessitating seating of the standing valve 156, the latter preferably having a delayed seating action as more fully discussed in my aforementioned copending application. Reciprocable in the pump cylinder 226 is a pump piston or plunger 240 which is connected to the engine plunger 214 by a piston rod 242. As more fully discussed hereinafter, the piston rod 242 extends through the engine valve 62 and controls the operation thereof, the piston rod acting as a pilot valve.

Referring particularly to Fig. 12, the pump plunger 240 includes a plunger body 244 into the upper end of which the piston rod 242 is threaded. Threaded onto the lower end of the plunger body 244 is a fitting 246 having silver soldered therein a seat 248 for a working valve 250, shown as a simple ball valve. Upward movement of the working valve 250 is ilmited by a stop 252 which is clamped between the fitting 246 and the lower end of the plunger body 244, and which is providedwith apertures 254 therethrough for flow of production fluid i0 upwardly into a longitudinal passage 256 through the plunger body. The upper end of the passage 256 communicates with radial ports 258 through which production fluid may flow into the pump cylinder 226 above the pump plunger 240. As will be apparent, during the working stroke of the pump plunger 240, which is the upward stroke in the particular embodiment illustrated, the working valve 250 closes so that production fluid above the pump plunger 240 is displaced upwardly through the standing valve 200, production fluid from the well simultaneously being drawn into the lower end of the pump cylinder through the standing valves 156 and 232. During the return stroke of the pump plunger 240, which is the downward stroke thereof in the particular construction illustrated, the working valve 250 opens and the standing valve 232 closes so that production fluid is displaced from the lower end of the pump cylinder 226 into the upper end thereof past the working valve 250 and through the apertures 254, the passage 256 and the ports 258. During the return stroke, the standing valve 156 remains open due to the delayed action discussed in detail in my aforementioned copending application. The standing valve 200 also tends to remain open during the return stroke, except when the pump cylinder 226 is not completely filled.

Considering the fluid pressures which produce the reciprocatory movement of the piston means 58, comprising the plungers 214 and 240 and the piston rod 242, the upper end of the engine plunger 214 is always exposed to the fluid pressure in the return tubing 46 through the port means 120, Figs. 5, 23 and 24. The annular area at the upper end of the pump plunger 240, equal to the difference between the area of the pump plunger and the area of the rod 242, is always exposed to the fluid pressure in the production tubing 48 through the production fluid outlet 182, Figs. 8, 23 and 24.' The lower end of the pump plunger 240 is also exposed to the pressure in the production tubing 48 during its return, or downward, stroke due to opening of the working valve 250 and closing of the standing valve 232, and is exposed to the pressure of the fluid in the well during its working, or up ward, stroke. The annular area at the lower end of the engine plunger 214, equal to the difference between the area of the engine plunger and the area of the rod 242, is exposed to the pressure in the supply tubing 44 during the working, or upward, stroke and is exposed to the pressure in the return tubing 46 during its return, or downward, stroke. The manner in which the pressures in the supply and return tubings 44 and 46 are applied to the lower end of the engine plunger 214 by the engine valve 62 will be considered in detail hereinafter.

Considering how the return stroke of the piston means 58 is produced, it will be apparent that, since the pressure in the return column is applied to both ends of the engine plunger 214 during the return stroke, the engine plunger has applied thereto a downward pressure force equal to the product of the return column pressure and the area of the rod 242. Similarly, since, during the return stroke, the pressure in the production column is applied to both ends of the pump plunger 240, the pump plunger has applied thereto an upward pressure force equal to the product of the production column pressure and the area of the rod 242. Expressed more simply, the pressure in the return tubing 46 acts downwardly on an effective area equal to the area of the rod 242, and the pressure in the production tubing 48 acts upwardly on an effective area equalto the area of the rod. Thus, by maintaining the pressure in the return tubing 46 higher than the pressure in the production tubing 48, the return stroke of the piston means 58 will be eflected when the lower end of the engine plunger 214 is exposed to the pressure in the return tubing by the engine valve 62. As hereinbefore indicated, the pressure in the return tub ing may be maintained higher than the pressure in the production tubing by means of the control device 50 at,

the surface, and the pressure differential between the return and production columns can be varied at the surface. Consequently, t-he speed of the return stroke of the piston means 58 is controllable at the surface independently of the speed of the working stroke, and other factors, and may be any value whatsoever, as desired, which is an important feature of the invention.

The engine valve 62 Turning now to a consideration of the environment of the engine valve 62, the rod 242, as previously indicated, extends through the engine valve. The rod 242 is sealed at each end of the engine valve 62 by means of floating bushings, the floating bushings at the upper end of the engine valve being designated by the numeral 260, and those at the lower end thereof being designated by the numeral 262. As best shown in Fig. 13, the lowermost of the floating bushings 260 is seated against a bushing 264 inserted into the upper end of the valve body 212, which is tubular. The uppermost of the floating bushings 260 is seated against a bushing 266 pressed into the tube 210, this bushing having an internal thread for engagement with a tool for removing it from the tube 210. Thus the floating bushings 260 are retained between the bushings 264 and 266. Similarly, the floating bushings 262 are retained between a bushing 268, Fig. 13, inserted into the lower end of the valve body 212 and a bushing 270, Fig. 8, pressed into the tube 224 to which the pump cylinder 226 is connected. For convenience in manufacture, the bushings 262, 268 and 270 are identical to the bushings 260, 264 and 266, respectively, although, as will become apparent, the two sets of bushings, except for their rod scaling functions, perform somewhat different functions.

Considering the engine valve 62 itself, the engine valve is hydraulically operated under the control of the piston rod or pilot valve 242 to connect the lower end of the engine cylinder 208 alternately to the supply and return tubings 44 and 46 to produce reciprocatory movement of the piston means 58. The valve 62 governs with a threespeed action during the working stroke of the pump 42 and has a single-speed action during the return stroke thereof. Except for some important differences in mechanical structure, the engine valve 62 is basically quite similar to and operates in substantially the same manner as the engine valves disclosed in my Patents Nos. 2,311,- 157 and 2,580,657. Consequently, in order to avoid unnecessary descriptive matter in this specification, the

structure and operation of the engine valve 62 will be described herein only in a general way, except for the important differences in mechanical structure mentioned, which will be described in detail hereinafter.

Referring particularly to Figs. 15 and 16 of the drawings, and also to Figs. 23 and 24 thereof, the engine valve 62 includes a tubular valve member 272 which is disposed in the tubular valve body 212 and which encircles the rod 242, the valve member 272 having a sliding fit with both the valve body and the rod. Externally, the valve member 272 is of uniform diameter and, internally, the valve member is provided with a minor diameter 274 and a major diameter 276, the minor diameter being such as to receive the rod 242 with a sliding fit; With this constructioma differential-area valve member results, having a large annular area 278 at its lower end, and smaller inner and outer areas 280 and 282, respectively, at its upper end. The areas 280 and 282 are preferably equal and each is preferably equal to one half the area 278, the area 280 being equal to the difference between the cross-sectional areas of the rod 242 and the bore 276 and thus including the area of the lower side of an internal annular. channel 312 in the valve member 2.72 which is described hereinafter. The inner and outer annular areas 280 and 282 are separated from each other by a floating sleeve or bushing 284 which has a sliding :.fit with .the rod 242 :and a sliding fit with the major diameter 276 of the valve member 272. Thus the differential-area valve member 272 is similar in principle to those disclosed in my Patents-Nos. 2,081,220, 2,081,223, 2,134,174 and 2,204,120, except that, instead of being externally stepped, it is internally stepped and the resulting areas are separated by the floating sleeve 284, which are important features of the invention.

As shown in Figs. 13 to 15, 23 and 24, the operating fluid exhaust 124 in the valve body 212 communicates with the outer annular area 282 of the valve member 272 at all times, irrespective of whether the valve member is in its lower position, as shown in Figs. 13 and 23, or in its upper position, as shown in Figs. 14 and 24, downward movement of the valve member being limited by engagement thereof with the bushing 268 and upward movement of the valve member being limited by engagement thereof with the floating sleeve 284. Thus the outer annular area 282 is constantly exposed to the pressure in the return tubing 46. The operating fluid intake 82 is in constant communication with the inner annular area 280 through an external annular channel 286 and radial ports 288 in the valve member. Consequently, the valve member 272 is constantly biased downwardly by the pressure in the return column acting on the outer annular area 282 and the pressure in the supply column acting on the inner annular area 280, these areas being separated by the floating sleeve 284, as hereinbefore discussed. Accordingly, the valve member 272 may be moved into its lower position, as shown in Figs. 13 and 23, by connecting the large area 278 at the lower end thereof to the return column, and the valve member may be moved to its upper position, as shown in Figs. 14 and 24, by connecting the large annular area 278 to the supply column. The manner in which this is accomplished will be described hereinafter.

It is important to note that, during the upward or working stroke of the piston means 58, the valve member 272 is in its upper position and, during the downward or return stroke of the piston means, the valve member 272 in its lower position, except for the final increments 4 of upward and downward movement of the piston means. Consequently, during the upward or working stroke, friction between the rod 242 and the valve member 272 biases the valve member into its proper operating position, which is its upper position in this instance. Similarly, during the downward or return stroke, friction between the rod 242 and the valve member 272 biases the valve member downwardly into its proper operating position, which is the lower position thereof in this case. Consequently, there is no necessity for opposing friction between the rod 242 and the valve member 272 with fluid pressure, except at the extreme ends of the working and return strokes, which is an important feature of the invention.

Considering how the foregoing is accomplished, Figs. 13 and 23 of the drawings illustrate the positions of the rod 242 and the valve member 272 when the piston means 58 is at the extreme upper end of its stroke. Under such conditions, the valve member 272 has moved downwardly preparatory to beginning the downward, or return, stroke of the piston means. The upper end of the valve member 272 uncovers ports 290, Figs. 13, 15, 18 and 23, and places them in communication with the operating fluid exhaust 124 through the annular space around the floating sleeve 284. The ports 290 communicate with passages 292 which extend upwardly through the valve body 212 and communicate at their upper ends with an annular space 294 around the floating bushings 260. Referring to Fig. 8, the annular space 294 communicates at its upper end with longitudinal grooves 296 extending through the bushing 266 and leading to the interior of the tube 210. The interior of this tube communicates at its upper end with the lower end of the engine cylinder 208. Consequently, the lower end of the engine plunger 214 is placed in communication the'bperating fluid exhaust *124, wherebyto produce" the.=-downward orretum stroke of the piston means 58 by-means of the pressure diflerential between the return and productiontubings 46 and'48, as hereinbefore dis- "cussed; Thus the valve member 272, when in its lower position, as shown in Figs. 13 and 23 of the drawings,

' upwardstroke ofthe piston means 58. Considering how this-is accomplished, it will be noted that the annular channel 286 in the valve member 272 connects the tapcrating fluid intake 82 to the ports 290, whereby operating fluid flows upwardly through the passages 292, the annular space 294, the grooves 296, and the interior of the tube 210 into the lower end of the engine cylinder 208m act on the lower end of-the engine plunger 214. Thus the working or upward stroke of the piston means is -produced when the valve member is in its upper position.

i The foregoing description of the mannerin which the valve member 272 effects the return and working strokes is general only. For a complete description applied to a basically similar valve member, attention is directed to my aforementioned Patents Nos. 2,311,157 and 2,580,-

"Considering now how the lower end of the valve memher 272" is alternately connected to the supply and return tubings 44 and 46, to move the valve member to its upper and lower positions, respectively, attention is again directed to Figs. 13 and'23 of the drawings. As previously indicated, Figs.- 13 and 23 show the relative positions of the rod 242 and the valve member 272 at the extreme upper end of the travel of pistonmeans 58, the

valve member 272 having moved downwardly to initiate the downward'orreturn stroke. However, just before the rod 242 reached'the upper end of its stroke, the valve member 272 was in its upper position to effect'the working stroke. As the rod 242 approached the upper end of'its travel, longitudinal grooves 298 therein placed the annular space around the rod below the valve member 2711a; communication with the operating fluid exhaust 1-24through a port 300 in the bushing 268, a port 302 in the valve body 212, passages 304 in the valve body, ports 306 in the valve body, and passages 308 in the valve body. Thus theoperating fluid under pressure from the supply column constantly acting on the inner annular area 280 of the valve member 272 moves the valve memberinto its lower position, as shown in Figs. 13 and 23, this occurring by the time the rod 242 reaches the upper end of'its travel. Thereupon the downward or return stroke commences.

1.,Tl1e' valve member is moved upwardly into its upper position, shown in Figs. 14 and 24, in a somewhat similar manner. InFigs. 14 and 24 the rod 242 has reached the lowerl liinit of its. travel and the valve member 272 has moved 'upwardly'into its upper position to initiate the upward stroke. Just before the rod 242 reached the lower end of its travel, grooves 310 therein connected the' in'ternal annular channel 312 in the valve member 272-which internal annular channel always contains opcrating fluid under high pressure due to its communication with the operating fluid intake 82 through the ports 288 andthe channel 286, with-ports 314, Fig. 22, in the valvemember. The ports 314 extend outwardly into communication with an external annular channel 316 in the ,valve member which, when the valve member was in its lower positio'n, registered with ports 318 in the valve; body 212. The ports 318 communicate with longitudinal passages 320 in the valve body which lead downwardly to radial ports 322extending inwardly into communication with the lower end of the valve member. Thus operating fluid under pressure from the supply tubing 44is delivered to the lower end of the valve mem- 14 ber 272 'to act "on the annular area 278 thereof, thereby initiating upward movement of the valve member toward its upper position in preparation for the upper or working stroke. It should be pointed out that the valve member 272 is provided with ports 321 therein which communicate with the operating fluid exhaust 124, through a passage 319, the passages 292 and the ports 290, when the valve member is in its lower position, Fig. 13, to hold the valve member down. Since the ports 321 communi-v cate with the lower end 278 of the valve member 272, through passages 323, itis necessary that the pressure drop through the ports 321 greatly exceed the pressure drop through the grooves 310 in the valve rod 242. Thus, when the grooves 310 connect the lower end 278 of the valve member 272 to the operating fluid intake 82 as hereinbefore described, suflicient pressure is applied to the lower end of the valve member to initiate upward movement thereof. The upward movement of the valve member 272 is completed by applying the operating fluid pres-. sure to the area 278 of the valve member through other passages which it is thought unnecessary to describe herein.

The foregoing is only a general description of the manner in which the valve member 272 is moved between its upper andlower positions. For a complete description; attention is again directed to my aforementioned Patents Nos. 2,311,157 and 2,580,657.

Another important feature of the invention. resides in the mechanical structure of the valve body 212. As shown throughout Figs. 13 to 16 and 18 to 22 ofvthe drawings, the valve body 212 includes an inner sleeve 324 and an outer sleeve 326 secured together in a fluidtigh-timanner, the aforementioned O-rings 92 and 94 en circling the inner sleeve 324 and engaging the ends of the. outer sleeve 326. Various ones of the passages in the valve body 212, such as the hereinbefore described passages 308 and 320, are located at the interface between the inner and outer sleeves, and are preferably grooves formed in the inner sleeve 324 for manufacturing convenience. These grooves in the inner sleeve 324 are closed by the outer sleeve 326 to form the desired passages, such as the passages 308 and 320. In order to proyideya fluid-tight fit between the inner and outer sleeves 324 and 326, the inner sleeve may be pressed into the outer sleeve, or the outer sleeve may be shrunk onto the inner sleeve. This construction for the valve body 212 greatly simplifies manufacture and results in a minimum number of drilled ports and passages, which is an important feature of the invention.

Operation 7 Considering now the over-all operation of the invention, it will be assumed that the tubing system 38 and the bottom-hole assembly 40 have been run into thewell, but thatthepump 42 has not yet been installed in its operating position. In order to install the pump 42, the closure 207 is removed and thepump is inserted into the upper end of the production tubing 48. By means of the control device 50, operating fluid from the supply pipe 52 is directed into the production tubing 48 above the pump to displace the pump downwardly into its operating posi tio n,'*any fluid in the production tubing below the pump being displaced upwardly to the surface through the supply and return tubings 44 and. Ultimately, the pump 42 enters the bottom-hole assembly 40 and seats on the seat 164 provided by the stand-ing valve assembly 154. When the pump 42 is in its operating position, the O-rings 114, 92, 94 and 148 engage the respective sleeves 1'12, 88, and 146, and the packer cup 205 is disposed within the enlarged counterbore 203. Under such conditions, the production fluid inlet 168 communicates only with the well; the production fluid outlet 182 communicates only with the production tubing 48, the operating fluid intake 82 communicates only with the supply tubing 44, and the port means and the operating fluid ex-' haust 124 communicate only with the return tubing 46. Thus the pump 42 is now ready for operation, being held on its seat 164 by the pressure in the production column thereabove. The production column pressure acts downwardly on the entire area of the pump 42, whereas the return column pressure acts upwardly on only the difference between the areas 17-2 and 170, Fig. 11. Thus there is a pressure force differential acting downwardly to hold the pump 42 on its seat.

Afiter the pump is in its operating position, the control device 50 is operated to connect the supply, return and production tubings 44, 46 and 48 to the supply, return and production pipes 52, 54 and 56, respectively, with a back pressure applied to the return tubing 46 to maintain the pressure therein higher than that in the .production' tubing 48. This maintains the pressure .difierential between the return and production tubings .46 and 48 necessary to effect the return stroke of the piston means 58.

Considering the operating fluid flow through thepump 4-2, the operating fluid under pressure fiows'downwardly through the supply tubing 44, through the upper sealing collar 66, and'through the pipe 72, the bore 74, the passage 78, and the main bore -80 into the operating fluid intake 82 of the pump. The piston rod'or pilot valve 242 and the differential-area valve member 272 cooperate to connect the lower end of the engine plunger 214 to the operating fluid intake 82 and the operating fluid exhaust 124 alternately. The exhaust 124 communicates with the return tubing 46 through the counterbore 122 and the annular space 118, Fig.8, and through the bore 106, the passage 104, the bore 102, the passage 100 and the bore 98, Fig. 6. The upper end of the engine cylinder 208 is in constant communication with the return tubing 46 through the port means 120, the annular space 118, and the bore 106, 'Fig. 5, and through the passage 104, the bore 102, the passage 100 and the bore 98, Fig. 6. Thus the upper end of the engine plunger 214 is constantly exposed to the pressure inthe return tubing 46, while the lower end of the engine plunger is alternately exposed to the pressures in .the supply and return tubings .44 and 46.

The upper end of the pump plunger 240 is constantly V exposed to the pressure in the production tubing 48 through the production fluid outlet 182 and the annular space 180, Fig. 8, through the passage 184, the bore 186 and the pipe 188, Fig. 11, and, Fig. 5, through thepassage 19.1, the groove 192, the ports 193, the grooves 194 and 195, the ports 197, the bore 198, the standing valve 200, the ports 201 and 202, and the counterbore 203. The lower end of the pump plunger 240 is alternately exposed to the pressure in the well and to the pressure in the production column. Exposure of the lower endof the pump plunger to the fluid pressure in the well takes place through the fitting 228, the apertures 236, the standing valve 232, which opens during the working stroke of the piston means 58, and through the inlet 1 68 and the standing valve assembly 154, all as shown in Fig. 11. During the return stroke, the standing valve 232 closes and the Working valve 250 carried by the pump plunger opens to connect the lower end of the pump plunger to the upper end thereof, thereby exposing the lower end ofthe pump plunger to the production column pressure. in the same manner as the upper end of the pump plunger.

Under the foregoing conditions, when the lower .end of the engine plunger 214 is connected-to the supply tubing 44 by the engine valve 62 in themannerdescribed, the piston means 58 is moved upwardly toaccomplish the working stroke thereof. Under such conditions production fluid is discharged into the production tubing 48 along the avenue described, and production .fluid from the well is drawn into the lower end of the pump cylinder along the avenue described. At the end of the working stroke, the engine valve 62 connectsthe lower end of the ss a n ugss 91. to heretum,tubin Ana i s s s t 16 and the standing valve .232 closes and the working .valvs 250 opens to expose the lower end of the pump plunger. 24.0. to. the pressure in the production tubing'48. Thus, under such conditions, the upper and lower. ends of the engine plunger 214 are'exposed to t e return column pressure and the upper and lower ends of the pump plunger 2510 are exposed to. the production column pressure.-

The return column pressure acts downwardly on IhBPiS'. ton means on an elfecti-ve area equal to the area of Ithe piston rod 242, while the production column pressure acts upwardly on the piston means on the same effective area. Since the return column pressure -is maintained at a higher value than the production column pressure by applying a back pressure to the return tubing .46 gtlhe surface by means of the control device 5!), a downward pressure force differential acts on the piston means 58 toefiect the return stroke thereof, which is an important feature of the invention. By accomplishing the return stroke of the piston means in this manner, the speed of the return stroke m y be c n roll d a hesurface indcpendently of all other factors so that the speed of the.

return stroke m y e any d s ed value, which is anim- Por ant feature F r e ample, the speed f h return stroke may be equal to, or greateror less than, the speed of the working stroke.

It shouldbe noted that due tothe hereinbefore described operation of the engine valve 62, the valve member 272 is in its upper position during the upward, working stroke of the piston means 58, and is in its lower position during the downward, return stroke thereof, except for ,the final increments of movement of the piston means, con: sequently, during the working and return strokes, I Ion between the rod 242 and thevalve member .272 .u 'gfi th valve member into its proper operating position, which is an important feature.

he it i d i ed t r mo e th pump 421mm the well for repair or replacemenhhthe control device 0j operated to connect the u p n n 5. t the-ret rn tubing 4, a to close t u p mbiqss fl 9 Disti tion tubing 48 remaining connected to the production pipe- 56 Un s h n h opera n fluid unde 2: u fl downwardly th h h r tu t biu fifi ihc lower end of the pump 42 by wayof the bore 9 8, the passage 100, the bore 102, the passage 104,.the bore 106 and .the annular space 118, Fig. 6, the counterbore 12}, the passage 126, the,bore 128, the passage 130, thebore 132 and the pipe 134, Fig. 10, and'.;the bore 136 and passage 138, Fig. 11. Thepressure oftheoperating thus delivered to the lower end of the pump" ,42 acts upwardly on an annular area thereof equal 911161116615- ence between the areas 1;7 2 and tdunseatthe this pressure acting on the entire area of the pump the moment the pump has been unsealed, .backflow'..into .llie well being prevented by thestanding valve ziss'emtsi 'rsli. By the time the pump has been movedftipwardlyisifificiently that the various O-ringson the exterior disengage the corresponding sleeves, the packer p p. 20,5 enters the production tubing ,48 to provide afluid -ti ght seal to prevent bypassingthe pump ,42. COnti'nued delivery of operating fluid below the pumpthrough ,the return tubing 46, or throughboth .the..supply.and.return tubings 44 and .46, resultsin upward displacementoflthe pump through the production tubing 48 .to thesunface. When the pump 42 arrivesat the"surface, the :tapered nose 206 at the upper end of the packer mandrel engages the catcher, not shown, carried by'the removable closure 207, whereupon the pump mayheiie moved from the production tubing 48 byii'eiinoving ,the closure. i I I Although I have disclosed an exemplary embodiment of the invention, .it will be understand that if s changes, modifications andf suhs'titution's maybe porated in suchembodinient, and that ea u es or the inven o may ut l ze i 99 9 WEE? 17 embodiments, all without departing from the spirit of the invention as defined by the claims hereinafter appearing.

I claim as my invention:

1. In Combination withsupply mcans'containing operating fluid under substantially constant high pressure and return and production means respectively containing spent operating fluid and production fluid at substantially constant pressures lower than said high pressure, a singleacting fluid-operated pump actuable by operating fluid under said high pressure from said supply means to discharge spent operating fluid and production fluid into said return means and said production means, respectively at said lower pressures, including: engine-and pump piston means movable through working and return strokes; means for applying said high pressure and said lower pressures to said piston means, during said working stroke thereof; and means for applying only said lower pressures to said piston means during said return stroke thereof, whereby none of said operating fluid under high pressure. is utilized during said return stroke.

2. A combination according to claim 1 wherein the means last defined includes means for applying said lower pressures to equal and'opposite areas of said piston means during said' return stroke, one of said lower pressures being higher than the other to effect said return stroke.

3. In combination with means providing a supply column containing operating fiuidunder substantially constant high pressure and return and production columns respectively containing spentop erating, fluid and production fluid at substantially"constant pressures lower than said high pressure, a single-acting fluid-operated pump actuable by operating fluid under said high pressure from said supply column to discharge spent operating fluid and production fluid into said return column and said production column, respectively, at said lower pressures, including: engine and pump piston means movable through working and return strokes; means for applying said high pressure from said supply column and said lower pressures from said return and production columns to said piston means during said working stroke thereof; and means for applying only said lower pressures from said return and production columns to said piston means during said return stroke thereof.

4. A combination according to claim 3 wherein the means last defined includes means for applying said lower pressures from said return and production columns to equal and opposite areas of said piston means during said return stroke, one of said lower pressures being higher than the other to effect said return stroke.

5. A combination as defined in claim 4 wherein said one lower pressure is the pressure of said return column.

6. In a single-acting fluid-operatedpump system, the combination of: a combination as defined in claim 5; and means remote from said pump for varying said one lower pressure to vary the speed of said'piston means during said return stroke.

7. In combination with means providing a supply column containing operating fluid under substantially constant high pressure and return and production columns respectively containing spent operating fluid and production fluid at substantially constant pressures lower than said high pressure, and in combination with a single-acting fluid-operated pump which is actuable by operating fluid under said high pressure from said supply column to discharge spent operating fluid and production fluid into said return and production columns, respectively, at said lower pressures, and, which includes engine and pump piston means movable through working and return strokes, means for eflecting said return stroke of said piston means, including: means for applying one of said lower pressures to an area of said piston means; and means for applying the other of said lower pressures to an equal and opposite area of said piston means, said one lower pressure being higher than said other lower pressure to elfect said return stroke.

8. In -combination with means providing a supply column containing operating fluid under substantially constant high pressure and return and production columns respectively containing spent operating fluid and production fluid at substantially constant pressures lower than said high pressure, and in combination with a single-acting fluid-operated pump which is actuable by operating fluid under said high pressure from said supply column to discharge spent operating fluid and production fluid into said return and production columns, respectively, at said lower pressures, and which includes engine and pump piston means movable through Working and return strokes, means for effecting said return stroke of said piston means, including: means for applying one of said lower pressures to an area of said piston means; and means for applying theother of said lower pressures to an equal and opposite area of said piston means, said one lower pressure being higher than said other lower pressure to eiiect said return stroke, said one lower pressure being the pressure in said return column. '9. In a fluid-operated pump system, the combination 7 of a fluid-operated pump having engine and pump piston means movable through working and return strokes; means for applying an operating fluid under pressure to said piston means to effect said working stroke, including control means carried by said pump and regulating the application ofsaid operating fluid to said piston means for controlling the speed of said piston means during said Working stroke; and means for eifecting said return stroke, including another control means independent of the first control means mentioned and remote from said pump for controlling the speed of said piston means during said return stroke.

10. In a single-acting fluid-operated pump, the combination of: a pump body having an intake for operating fluid, an exhaust .fo-r spent operating fluid, an inlet for production fluid, and an outlet for production fluid; engine and pump piston means movable in said pump body through working and return strokes and having a plurality of areas; means for connecting said areas of said piston means to said intake, said exhaust, said inlet and said outlet during said working stroke; and means for connecting said areas of said piston means to said exhaust and said outlet only during said return stroke.

11. A single-acting fluid-operated pump as defined in claim' 10 wherein said piston means includes an upwardlyfacing area at an upper end thereof in constant communication-with said exhaust, and includes a downwardlyfacing area at a lower end thereof in alternate communication with said inlet and said outlet.

12. A single-acting fluid-operated pump as defined in claim 11 wherein said piston means includes a downwardly-facing area intermediate said upper and lower ends thereof in alternate communication with said intake and said exhaust, and includes an upwardly-facing area intermediate said upper and lower ends thereof in constant communication with said outlet.

13. In a single-acting fluid-operated pump, the combination of: a pump body having an intake for operating fluid, an exhaust for spent operating fluid, an inlet for production fluid, and an outlet for production fluid; engine and pump piston means movable in said pump body through working and return strokes, said piston means including an upper, engine plunger and a lower, pump plunger connected by a rod; means for constantly con-- necting the upper end of said engine plunger to said exhaust; means for alternately connecting the lower end of said engine plunger to said intake and said exhaust; means for constantly connecting the upper end of said pump plunger to said outlet; and means for alternately connecting the lower end of said pump plunger to said inlet and said outlet.

14. A single-acting fluid-operated pump system, including: a single-acting fluid-operated pump as defined 19 in claim 13; and means remote from said pump for maintaining the pressure at said exhaust higher han the pressure at said outlet.

15. A single-acting fluid-operated pump according to claim 13 wherein said means for alternately connecting said lower end of said engine plunger to said intake and said exhaust includes an engine valve located between said engine and pump plungers and encircling said rod.

16. In a closed, single-acting, fluid-operated pump system, the combination of: a supply tubing for operating fluid, a return tubing for spent operating fluid, and a production tubing for production fluid, all set in a Well; a single-acting fluid-operated pump in the well and including engine and pump piston means movable through working and return strokes, said pump including means for applying pressure from said supply tubing to an area of said piston means to eflect said working stroke, and including means for applying to equal and opposite areas of said piston means the pressures in said return and production tubings during said return stroke, so as to effect said return stroke in response to .a pressure differential between said return and production tubings; and means at the surface for maintaining a fluid pressure dif ferential between said return and production tubings.

17. A system as defined in claim 16 wherein said tubings are interconnected in fluid communication at their lower ends and wherein said pump is a free pump movable downwardly through one of said tubings into an operating position at the lower end thereof wherein it communicates with said tubings.

18. A system as defined in claim 17 wherein said free pump is movable through said production tubing.

References Cited in the file of this patent UNITED STATES PATENTS 1,568,447 Forsyth Jan. 7, 1926 1,757,329 Neilsen "May 6, 1930 1,887,736 Scott Nov. 15, 1932 1,899,697 Kibele et a1. Feb. 28, 1933 1,909,493 Knox May 16, 1933 2,081,220 Coberly May 25, 1937 2,081,223 Coberly May 25, 1937 2,134,174 Coberly Oct. 25, 1938 2,204,120 Coberly July 11, 1940 2,273,349 Farley et al. Feb. 17, 1942 2,277,181 Zuc'k Mar. 24, 1942 2,291,880 Coberly Aug. 4, 1942 2,311,157 Coberly Feb. 16, 1943 2,479,864 Coberly June 21, 1949 2,508,174 Knox et al. May 16, 1950 2,580,657 Coberly Jan. 1, 1952 2,631,541 Dempsy Mar. 17, 1953 2,651,914 Joy Sept. 15, 1953 2,653,545 Dempsey Sept. 29, 1953 2,716,425 Yarber Aug. 30, 1955 2,762,309 Knox Sept. 11, 1956 FOREIGN PATENTS 651,555 Great Britain Apr. 4, 1951 

